Haloforms have recently been identified in municipal water supplies and appear to be formed during the chlorination process. Furthermore, chloroform has recently been shown to be a carcinogen in both rats and mice. The objective of the proposed research is to elucidate the bioorganic mechanism for the metabolism of haloforms to carbon monoxide and carbon dioxide. An investigation of the covalent interaction of haloforms with cellular macromolecules, lipids and glutathione is also planned. Finally, an attempt will be made to structurally identify the compounds formed by interaction of reactive intermediates with nucleic acids, proteins and lipids.